U.S. patent application number 11/908840 was filed with the patent office on 2009-01-29 for metal material, and coating film and wiring for semiconductor integrated circuitry utilizing the metal material.
This patent application is currently assigned to NEC CORPORATION. Invention is credited to Akio Tanikawa.
Application Number | 20090029126 11/908840 |
Document ID | / |
Family ID | 36991456 |
Filed Date | 2009-01-29 |
United States Patent
Application |
20090029126 |
Kind Code |
A1 |
Tanikawa; Akio |
January 29, 2009 |
METAL MATERIAL, AND COATING FILM AND WIRING FOR SEMICONDUCTOR
INTEGRATED CIRCUITRY UTILIZING THE METAL MATERIAL
Abstract
When metallic material is employed for various metallic films,
it is possible to improve at least one of the mechanical strength,
the durability against abrasion, and the uniformess as a film while
keeping unchanged the chemical property and the electric property
of the metallic material. Due to the gel three-dimensional mesh
structure 406, the dislocations 407 of the tangle in the mesh form
are introduced in the crystal of the metal 401 at high density;
therefore, when the tensile stress 403 is applied thereto, these
dislocations slightly shift. As a result, the metal 401 deforms by
uniformly dispersing distortion in the order of crystal grains, and
hence there does not occur concentration of stress, which leads to
the breakage or the severance at the grain interface 402.
Therefore, the metallic material of the present invention improves
the mechanical strength and the durability against abrasion.
Inventors: |
Tanikawa; Akio; (Tokyo,
JP) |
Correspondence
Address: |
YOUNG & THOMPSON
209 Madison Street, Suite 500
ALEXANDRIA
VA
22314
US
|
Assignee: |
NEC CORPORATION
Tokyo
JP
|
Family ID: |
36991456 |
Appl. No.: |
11/908840 |
Filed: |
February 7, 2006 |
PCT Filed: |
February 7, 2006 |
PCT NO: |
PCT/JP2006/302091 |
371 Date: |
October 6, 2007 |
Current U.S.
Class: |
428/209 |
Current CPC
Class: |
H01L 21/2885 20130101;
C23C 30/00 20130101; H01L 21/28556 20130101; H01L 21/2855 20130101;
C22C 9/00 20130101; C22F 1/08 20130101; C23C 28/02 20130101; H01L
21/76838 20130101; C25D 3/02 20130101; H01L 21/288 20130101; Y10T
428/24917 20150115; H05K 1/09 20130101; C23C 26/00 20130101 |
Class at
Publication: |
428/209 |
International
Class: |
B32B 3/10 20060101
B32B003/10 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 16, 2005 |
JP |
2005-074306 |
Claims
1-7. (canceled)
8. A metallic material characterized by comprising, in a
transmission electron microscope image, crystal grains observed to
be filled up with moire patterns that are amorphously subdivided
and that have variable intervals and angles.
9. The metallic material in accordance with claim 8, characterized
by comprising crystal grains providing moire patterns whose
intervals are equal to or less than ten nanometers.
10. The metallic material in accordance with claim 8, characterized
by comprising crystal grains including subdivided areas of moire
patterns, the subdivided areas having a mean size equal to or less
than 50 nm.
11. The metallic material in accordance with claim 8, characterized
by comprising a structure in which metal is densely filled in gaps
in a network structure of gel.
12. The metallic material in accordance with claim 8, characterized
by comprising copper as a base thereof.
13. Wiring for semiconductor integrated circuits, comprising
metallic material that includes, in a transmission electron
microscope image, crystal grains observed to be filled up with
moire patterns that are amorphously subdivided and that have
variable intervals and angles.
14. A coating film for electric tools, mechanical parts, or optical
parts, comprising the metallic material that includes, in a
transmission electron microscope image, crystal grains observed to
be filled up with moire patterns that are amorphously subdivided
and that have variable intervals and angles.
15. The wiring for semiconductor integrated circuits according to
claim 13, wherein the metallic material includes crystal grains
providing moire patterns whose intervals are equal to or less than
ten nanometers.
16. The wiring for semiconductor integrated circuits according to
claim 13, wherein the metallic material includes crystal grains
including subdivided areas of moire patterns, the subdivided areas
having a mean size equal to or less than 50 nm.
17. The wiring for semiconductor integrated circuits according to
claim 13, wherein the metallic material includes a structure in
which metal is densely filled in gaps in a network structure of
gel.
18. The wiring for semiconductor integrated circuits according to
claim 13, wherein the metallic material includes copper as a base
thereof.
19. The coating film according to claim 14, wherein the metallic
material includes crystal grains providing moire patterns whose
intervals are equal to or less than ten nanometers.
20. The coating film according to claim 14, wherein the metallic
material includes crystal grains including subdivided areas of
moire patterns, the subdivided areas having a mean size equal to or
less than 50 nm.
21. The coating film according to claim 14, wherein the metallic
material includes a structure in which metal is densely filled in
gaps in a network structure of gel.
22. The coating film according to claim 14, wherein the metallic
material includes copper as a base thereof.
Description
TECHNICAL FIELD
[0001] The present invention relates to metallic material, and in
particular, to metallic material to be used for a metallic coating
film employed in semiconductor devices and electronic
apparatuses.
RELATED ART
[0002] For a metallic film used for various purposes, a function
corresponding to the purpose as well as high durability and
mechanical strength are required.
[0003] For example, for the wiring of a semiconductor integrated
circuit, there are employed an aluminum alloy film by a sputtering
scheme, a copper film by a plating scheme, and the like. Also, in
electric tools such as electrodes and connectors, a coating film of
gold, silver, or the like is disposed by a sputtering scheme or a
plating scheme with the view of lowering junction resistance; in
mechanical parts such as screws and bolds, a coating film of
nickel, chromium, or the like is arranged for the purpose of
preventing rust. Incidentally, as a technique associated with
wiring having high mechanical strength, patent document 1 describes
wiring in multilayer structure. Moreover, as techniques applying
gel, patent document 2 describes metallic wiring using as an
underlay a porous film formed in sol-gel method, and patent
document 3 describes metallic parts produced by making metal
percolate into a mold, which is created by shaping by a binder
obtained by gelated alumina fiber and by hardening (a kind of
sol-gel method) thereafter.
Patent document 1: Japanese Patent Laid-open Pub. No. Hei5-198691
Patent document 2: Japanese Patent Laid-open Pub. No. 2003-51463
Patent document 3 Japanese Patent Laid-open Pub. No.
Hei7-252556
DISCLOSURE OF THE INVENTION
Problem to be Solved by the Invention
[0004] In the conventional metallic film of wiring in semiconductor
integrated circuits, the wiring is disconnected and hence
reliability of the semiconductor integrated circuits cannot be
retained in some cases. Moreover, for the coating film of the
electric tools and the mechanical parts, there are required higher
mechanical strength and superior durability against abrasion. Also,
for these metallic films, there is required a production method to
more easily secure uniformess.
[0005] The present invention has been devised to meet the
requirements and has an object to provide compound metallic
material usable for various metallic films and a production method
thereof in which while keeping unchanged a chemical property and an
electric property of metallic material (metal filled in gaps in a
three-dimensional mesh structure), the mechanical strength, the
durability against abrasion, and the uniformess as a film are
improved. As a result, there is provided wiring which is not easily
disconnected and which is superior in the securing of reliability
from a viewpoint of the uses for semiconductor integrated circuits,
and there is provided a coating film having higher mechanical
strength and superior durability against abrasion from a viewpoint
of the uses for the coating of electric tools such as connectors
and the coating of mechanical parts or optical products.
Means for Solving the Problem
[0006] To achieve the objects, there is provided metallic material
in accordance with an aspect of the present invention in which gaps
of a gel network structure including crystal grains are densely
filled up with metal, the crystal grains, in a transmission
electron microscope image, being observed to be filled up with
moire patterns which are amorphously subdivide and which have
variable intervals and angles.
[0007] Moreover, the interval between the moire patterns may be set
to 10 nanometers (nm) or less and the mean size of the subdivided
areas is set to 50 nm or less. The network structure is a
three-dimensional mesh structure formed through crosslinking or
tangling of polymer in which atoms or molecules (monomer) are
chained with each other in a one-dimensional way. The crystal
lattice of metal densely filled in gaps in the gel network
structure shifts for each gap due to the one-dimensional polymer
molecules and is distorted. Therefore, in a transmission electron
microscope image, there is observed as if the crystal grains are
filled up with moire patterns which are amorphously subdivide and
which have variable intervals and angles.
[0008] According to these metallic materials, while keeping
unchanged the chemical property and the electric property of metal
filled in gaps in the three-dimensional mesh structure (to be
referred to as metal filled therein or metal to be filled therein
depending on cases.), the mechanical strength and the durability
against abrasion are improved.
[0009] Additionally, according to these metallic materials, the
density of the metallic material in the three-dimensional mesh
structure can be uniformly controlled with satisfactory
reproducibility through (i) selection of the kind of gel used for
the three-dimensional mesh structure, (ii) selection of a method to
produce the three-dimensional mesh structure, (iii) adjustment of
the amount of the solvent contained in the gel formed on a
substrate in the production process of the three-dimensional mesh
structure. As a result, it is possible to control the dislocation
density of the filled-in metal and to uniformly introduce
dislocation of metal with satisfactory reproducibility.
[0010] Furthermore, according to (iii) adjustment of the amount of
solvent, the ratio in terms of volume or weight of the
three-dimensional mesh structure to the solvent can be set to one
percent or less and hence the amount of the three-dimensional mesh
structure relative to the metal to be filled therein can be
precisely adjusted. Therefore, the three-dimensional mesh structure
becomes impurity and it is hence possible to prevent change in the
chemical property such as resistivity against medicines and the
electric property such as electric resistance of the metal filled
therein. Resultantly, it is possible to easily produce metallic
material which has high mechanical strength and superior durability
against abrasion while keeping unchanged the chemical property and
the electric property of the filled-in metal.
[0011] Incidentally, the ratio in terms of volume of the
three-dimensional mesh structure to the solvent in the description
is a value obtained by dividing the difference between the volume
of the gel including the solvent and the volume of only the solvent
in the situation (the volume of the three-dimensional mesh
structure of the gel) by the volume of the gel including the
solvent. Also, the ratio in terms of weight of the
three-dimensional mesh structure to the solvent in the description
is a value obtained by dividing the weight (the weight of the
three-dimensional mesh structure of the gel) of the gel from which
the solvent is dried up (to be called dried gel) by the sum of the
weight of the dried gel and that of the solvent. In this situation,
it is assumed that the solvent is water; if the solvent is other
than water, the calculation is conducted by replacing the weight of
the solvent by the weight of water of the same volume of the
solvent.
[0012] According to the metallic material of the present invention,
there can be obtained a metallic film that has high mechanical
strength and superior durability against abrasion while keeping
unchanged the chemical property and the electric property of the
filled-in metal. For example, when the metallic material is
employed for the wiring in semiconductor integrated circuits, the
wiring is not easily disconnected, and hence highly reliable
semiconductor integrated circuits are obtained. In addition, when
the metallic material is employed for the coating film of
mechanical parts or the like, there is produced a coating film
which has high mechanical strength and high durability against
abrasion and which is not easily peeled off from the substrate.
[0013] According to the metallic material of the present invention,
while keeping unchanged the chemical property and the electric
property of metal filled in gaps in the three-dimensional mesh
structure (to be referred to as metal filled therein or metal to be
filled therein depending on cases.), the mechanical strength and
the durability against abrasion are improved.
[0014] The network (three-dimensional mesh structure) of gel is
formed through the crosslinking or tangling of polymer in which
atoms or molecules (monomer) are chained with each other in a
one-dimensional way. The crystal lattice of the metal densely
filled in gaps in the network structure of the gel shifts for each
gap by one-dimensional polymer molecules and is hence distorted.
Therefore, the material is observed in a transmission electron
microscope image to be filled up with moire patterns which are
amorphously subdivided and which have variable intervals and
angles. It is a feature of the metallic material of the present
invention that although the gel network itself is not observed, the
material is filled up with moire patterns which are amorphously
subdivided and which have variable intervals and angles; therefore,
it can be identified that the gel in which the gel network is
filled in the metal or the gel in which the gel network was filled
in the metal has denatured.
[0015] The mechanical strength and the durability against abrasion
are improved while keeping unchanged the chemical property and the
electric property of metal filled in gaps in the three-dimensional
mesh structure of the gel because dislocation or a lattice defect
structure which may become a dislocation source can be introduced
into the crystal lattice of the filled-in metal centered on a
one-dimensional chain (formed through the chaining of
one-dimensional coupling of gel atoms or molecules) of gel forming
the three-dimensional mesh structure, not because impurity atoms
are simply added to the metal. That is, the crystal of the
filled-in metal is in the state in which the dislocation of the
tangling or tangle in the mesh form is introduced at high density,
and the dislocation exerts two actions as below, and hence the
above effect is attained.
[0016] First, the first action will be described.
[0017] In the metallic material of the present invention, since the
dislocation of the tangle in the mesh form is introduced in the
crystal of the metal at high density, the lattice defect of the
metal changes in the order of nanometer and hence the lattice
distortion is not uniform in this state. In general, when external
force is applied onto metal, atoms of the metal are going to
diffuse; however, in the metallic material of the present
invention, the non-uniform lattice distortion bents the diffusion
paths of metallic atoms in a complex way. As a result, the speed of
plastic deformation due to the self-diffusion of the filled-in
metal is lowered, and hence the mechanical strength and the
durability against abrasion are improved.
[0018] Next, the second action will be described by referring to
drawings.
[0019] In general, as FIG. 1(a) shows, when tensile stress 403 is
applied to metal 401, dislocation 405 included in the crystal of
the metal is brought into activity, and hence stress is
concentrated onto an interface 402 between grains of the metal 401
and a void (crack) 404 grows. Therefore, breakage and severance
easily occur in the conventional metal 401, which hence has low
mechanical strength. On the other hand, in the metallic material of
the present invention, as FIG. 1(b) shows, since the dislocation
407 of the tangle in the mesh form is introduced in the crystal
grains of the metal 401 at high density due to the
three-dimensional mesh structure 406 of gel, when the tensile
stress 403 is applied thereto, these dislocations slightly shift.
As a result, the metal 401 deforms by uniformly diffusing the
distortion in the order of the crystal grain, and hence there does
not occur the concentration of stress at the interface 402 between
grains, the concentration of stress causing the breakage or the
severance. Therefore, the mechanical strength and the durability
against abrasion are improved in the metallic material of the
present invention. Incidentally, in FIG. 1, the three-dimensional
mesh structure 406 is shown by solid lines and the mesh structure
407 of the dislocation is shown by broken lines. Also, in the
present specification, "dislocation" is a kind of lattice defect
and indicates a dislocation of a string of atoms occurring along a
line (dislocation line) in the crystal.
[0020] Furthermore, according to the metallic material of the
present invention, thanks to the two actions, when the metallic
material is formed into a metallic film on a substrate, the
interface stress between the metallic film and the substrate can be
mitigated, and hence the metallic material becomes a metallic film
(coating film) which cannot be easily peeled off from the
substrate.
[0021] According to the method of producing the metallic material
of the present invention, various effects are obtained through
(iii) adjustment of the amount of the solvent described above. For
example, when the ratio in terms of volume or weight of the
three-dimensional mesh structure to the solvent is adjusted to 10%
or less, the change in the electric property of the filled-in metal
can be sufficiently suppressed. Also, when the ratio in terms of
volume is adjusted to 5% or less, the change in the tone of color
of the filled-in metal can be sufficiently suppressed. Furthermore,
when the ratio in terms of volume is adjusted to 20% or less, it
can be easily conducted in an operation to fill metal in gaps of
the three-dimensional mesh structure using the plating scheme to
densely fill the metal therein. Additionally, when the ratio in
terms of volume is adjusted to 2% or less, in an operation to fill
metal in gaps of the three-dimensional mesh structure using a
physical vapor deposition scheme, e.g., the sputtering scheme or
the evaporation scheme, it can be easily conducted to densely fill
the metal therein.
[0022] Moreover, through (iii) adjustment of the amount of the
solvent described above, the size of the mesh of the
three-dimensional mesh structure can be adjusted in a range from
several nanometers to several tens of nanometers, which can
implement both of the sufficient strength and the function
according to the purpose.
[0023] Furthermore, according to the method of producing the
metallic material of the present invention, since coarseness of the
surface of the substrate on which the metallic material is
constructed and the convection of the plating solution and the raw
material gas due to the concentration of electric fields, the
temperature difference, or the like are suppressed by the
three-dimensional mesh structure, the obtained metallic material
has uniform thickness. Therefore, when such metallic material is
employed for various metallic films, there is also obtained an
effect of improving the uniformess of the films.
EFFECT OF THE INVENTION
[0024] In accordance with the present invention, when the metallic
material is employed for various metallic films while keeping
unchanged the chemical property and the electric property of the
metallic material, it is possible to improve at least one of the
mechanical strength, the durability against abrasion, and the
uniformess as films.
EXEMPLARY EMBODIMENTS
[0025] The metallic material of the present invention is suitably
used as wiring of semiconductor integrated circuits or coating
films of electric tools, mechanical parts, or optical parts.
[0026] In the method of producing the metallic material of the
present invention, the effect is not lost even if (1) a process to
remove part of the three-dimensional mesh structure is disposed
before the process to fill in the metal, (2) a process to denature
part of the three-dimensional mesh structure is disposed after the
process to fill in the metal, and (3) a process to carbonize part
of the three-dimensional mesh structure is disposed after the
process to fill in the metal when the gel is formed using an
organic material.
[0027] Next, description will be given of the metallic material and
the production method of the material according to the present
invention by referring to drawings.
[0028] FIG. 2 is a schematic cross-sectional view showing an
example of the metallic material of the present invention. The
metallic material of the present invention is configured by filling
metal 103 in gaps in a (three-dimensional) mesh structure 102 of
gel. That is, when the configuration of metallic material of the
present invention is viewed from another viewpoint, the
three-dimensional mesh structure 102 of gel is disposed in a film
of the metal 103 in the construction. Moreover, although the mesh
structure 102 is disposed throughout the film of the metal 103, the
structure 102 does not mechanically support the film of the metal
103 from the inside.
[0029] FIG. 3 is a schematic diagram showing an example of the
metallic material of the present invention. By producing a foil of
the metallic material to observe the foil by a transmission
electron microscope, there is often observed crystal grains filled
up with moire patterns 202 which are amorphously subdivided and
which have variable intervals and angles as shown in FIG. 3. The
subdivided area in the area occupied by the moire patterns 202 has
a size 203 corresponding to width of a gel network 201 subdividing
the moire patterns 202, and the mean size thereof is 50 nm or less
and favorably ranges from two nanometers to 50 nm. The interval of
the moire patterns 202 caused by the overlapping of shifted crystal
lattices does not exceed ten nanometers. Although the moire pattern
202 is absent from some boundary areas, the width of the area is
less than the size of the moire area. This is because the crystal
lattices having structure in which metal is densely filled in gaps
in the gel network structure 201 are shifted in slightly different
angles for respective gaps by the one-dimensional polymer molecules
and hence are distorted. That is, if two or more gel gap areas
exist in the direction of incidence of electrons of the
transmission electron microscope, there are observed moire patterns
by the overlapping of the shifted lattices. These moire patterns
are amorphously subdivided according to a size matching the size of
the mesh of the three-dimensional mesh structure of gel; the
interval and the angle of the moire patterns are variable and are
fluctuating because the shift of crystal lattices is variable in
the mesh. The transmission electron microscope image filled up with
the moire patterns which are amorphously subdivided and which have
variable intervals and angles as above is observed throughout the
area of crystal grains matching the conditions of the crystal
orientation and thickness. This is a feature which is observed only
for the metallic material of the present invention.
[0030] The moire patterns described above are caused by shifted
crystal lattices, by neither composition and a phase change, nor
fringes of equal thickness, nor curved interference fringes. For
these, even if the orientation is changed, the fringe itself does
not disappear. Also, although the stacking fault causes patterns of
fringes by shifting crystal lattices, the area is discrete and
shows a polygonal form such as a triangle or a hexagon; moreover,
the fringes are equally separated from each other in many cases and
are linear, and hence these can be discriminated based on the
different points. Additionally, the gel network structure shows
amorphous shapes irrespective of crystal lattices unless a fine
periodic structure is intentionally constructed, and hence the
shapes of subdivided areas subdivided by the gel network structure
are amorphous. Furthermore, since the direction of the
one-dimensional polymer molecules constituting the gel network
structure is also determined irrespective of the crystal lattices,
the magnitude and the angle of distortion accordingly caused in the
crystal lattices of the metal are variable and hence the interval
and the angle of moire patterns are variable and fluctuate.
[0031] Incidentally, the metallic material of the present invention
is produced in a first production method in which a
three-dimensional mesh structure including solvent in gaps is
constructed by forming gel including a three-dimensional mesh
structure on a substrate, and then a metallic material is produced
by filling metal in the gaps by replacing the solvent with the
metal using the plating scheme and a second production method in
which a three-dimensional mesh structure including solvent in gaps
is constructed by forming gel including a three-dimensional mesh
structure on a substrate, the solvent is dried up by supercritical
drying or the like to construct a three-dimensional mesh structure
in which the gaps are not crushed and which does not include the
solvent, and a metallic material is produced by filling metal in
the gaps by the chemical vapor deposition method or the physical
vapor deposition method. The substance including only the
three-dimensional mesh structure in which the gaps are not crushed
and which does not include the solvent is called aerogel.
[0032] Incidentally, when colloid solution is heated or cooled, the
solution loses its fluidity and solidifies (grains connect to each
other to form a three-dimensional mesh structure) depending on
cases. The state in which the solution has lost the fluidity is
generally called gel. When water is forcibly removed from the gel,
there remains a porous structure in which grains are crushed to be
fixed to each other. Although this is also called a
three-dimensional mesh structure, this is not included in the
definition of gel in the present specification.
[0033] That is, the gel in the present specification is a substance
that has a three-dimensional mesh structure constructed by a
one-dimensional chain of atoms or molecules (a chain formed by
one-dimensional coupling of atoms or the like) and which includes
solvent in gaps therein. Moreover, the gel also includes a
substance including a structure in which such one-dimensional chain
of atoms or molecules and another one-dimensional chain form a
crosslink, the substance including solvent in gaps therein.
[0034] That is, in accordance with the present invention, the
three-dimensional mesh structure of gel includes a structure
including a crosslink structure and a structure not including the
crosslink structure. Additionally, even if the structure does not
include the crosslink structure, it may be a structure in which
one-dimensional chains intersect each other. However, the
three-dimensional mesh structure in the present specification must
absolutely include the one-dimensional chain of atoms or molecules.
In other words, the gel of the present invention does not include a
structure in which porous materials and grains couple with each
other even if the raw material is gel. In particular, porous
material obtained by the sol-gel scheme in which solid matter is
produced by hardening gel is only porous solid matter, which can
not be used in the present invention at all. Also, if the
one-dimensional chain of atoms or molecules is widely interpreted,
there is also included so-called fiber; however, to obtain the
effect of the present invention, it is required that the
one-dimensional chain of atoms or molecules (if chains constitute a
bundle, one of the chains of the bundle) has a diameter (thickness)
of 20 nanometers or less and ten nanometers or less to attain an
explicit effect.
[0035] In the first production method described above, as a plating
scheme employed to fill metal in the gaps in the three-dimensional
mesh structure, there may be considered an electrolytic plating
scheme or an electroless plating scheme; and from a viewpoint of
the densely filling in of metal, it is favorable to apply the
electrolytic plating scheme.
[0036] Metal filled in by applying the plating scheme may have a
multilayer structure of a plurality of kinds of metals. In this
case, it is easily constructed by soaking a substrate on which the
three-dimensional mesh structure is formed in plating solution of a
desired metal and thereafter by soaking the substrate in plating
solution of another metal.
[0037] After the metal is filled in the gap in the
three-dimensional mesh structure as above, it is favorable to
remove excessive gel according to necessity. For example, after a
slightly thicker gel is formed and the metal is filled therein with
a required thickness, the gel in which the metal is not filled is
removed. As a method to remove the gel, there may be employed a
method to conduct chemical-mechanical polishing or to conduct
washing by use of a jet water stream or water at 80.degree. C. or
higher. Also, by the chemical-mechanical polishing, it is possible
to remove an excessive portion of the filled-in metal together with
the excessive gel.
[0038] The solvent in the three-dimensional mesh structure of gel
formed on the substrate in the second production method is dried
not to crash the three-dimensional mesh structure of gel. As such
drying method, an ultra-critical drying method, a freeze-drying
method, or the like is applicable; the ultra-critical drying method
is favorable from the viewpoint that the three-dimensional mesh
structure is not crashed. The ultra-critical drying method is a
method to dry the solvent under a condition equal to or more than a
critical temperature and a critical pressure; since the surface
tension of the solvent is zero, the solvent is dried without
crashing the three-dimensional mesh structure.
[0039] As material gases employable in the Chemical Vapor
Deposition method (CVD method), there may be used inorganic metal
compounds such as wolfram halide and organic metal compounds such
as trimethylaluminum generally used in the CVD method. Furthermore,
as the Chemical Vapor Deposition method, the thermal CVD method,
the plasma CVD method, or the optical CVD method is available; and
as the method and conditions thereof, those generally known are
available. Incidentally, when metal is filled in by use of the
thermal CVD in the metallic material production process, it is
desirable to select from the gel materials, a gel material having
heat resistance against the metal growing temperature.
[0040] Additionally, in place of the CVD method, the physical vapor
deposition method is also available; as the filling-in of metal in
the physical vapor deposition method, there may be employed the
metal filling-in of the sputtering method and that of the
evaporation method. In a case wherein the metal is filled in by use
of the sputtering method or the evaporation method, in order to
enable to densely fill in the metal, it is favorable that a metal
which easily diffuses on the substrate surface is selected as the
metal to be filled in and the thickness of the metal is set to a
low value. Moreover, when the sputtering method or the evaporation
method is employed, although it is considered that material atoms
of the metal undergone the sputtering or the like are fixed, before
arriving at the substrate, onto the three-dimensional mesh
structure and the filling-in of the metal is slightly deteriorated,
the metal is densely filled in the gaps in the three-dimensional
mesh structure if the filling-in is carried out under the condition
described above.
Application Example
[0041] Referring to drawings, description will be given of an
application example of the present invention.
[0042] FIG. 4 shows as a specific example of application of a
metallic material of the present invention, a transmission electron
microscope image of a film in which agarose gel is buried in copper
to be used for wiring of a semiconductor integrated circuit (LSI).
FIG. 4(a) is an image of one crystal grain with an electron beam
incidence orientation <211>, namely, an orientation vertical
to the sheet of paper and the thickness condition is satisfied. The
crystal orientation in a plane is indicated by an arrow mark drawn
on the left side. Moire fringes appearing under this condition are
about in the <011> direction (a general term including all
orientations which include the <011> orientation and the
orientations equivalent to the <011> orientation; this also
applies to the description hereinbelow); and are caused by the
shift of the lattice image corresponding to the {022} lattice plate
having an interval which is one half of the {011} lattice plane
vertical to the moire fringes (a general term including all planes
which include the (001) plane and the planes equivalent to the
pertinent lattice plane; this also applies to the description
hereinbelow). The film includes crystal grains observed as if the
grains are filled up with moire patterns which are amorphously
subdivided and which have variable intervals and angles; and for
other crystal grains, there are observed moire patterns of
different patterns. FIG. 4(b) is an image of another crystal grain
with an electron beam incidence orientation <011>, namely, an
orientation vertical to the sheet of paper and the thickness
condition is another appropriate condition. Moire patterns appear
in two directions of a crystal orientation <111> in a plane
indicated by an arrow mark drawn on the left side, and resultantly,
there appear zigzag patterns. In this case, lattice images
corresponding to the {111} lattice plane form moire patterns. In
the case described above, any subdivided area has a size of about
ten nanometers and the moire interval ranges from one nanometer to
two nanometers. Furthermore, FIG. 4 includes a large number of
contrasts 301, 302, and 303.
[0043] Incidentally, the metallic material based on copper in the
specific example of the present invention does not show any change
after 30-minute heat treatment at 350.degree. C. In a case wherein
the copper film containing the three-dimensional mesh structure of
the gel is used to form LSI wiring, the disconnection ratio due to
stress migration and electromigration can be reduced to 1/1000 as
compared with the conventional copper wiring.
[0044] The film including the copper-based metallic material is
produced as follows. First, in a pre-process of the electrolyte
plating, a sputtered copper film having a thickness of about 100 nm
is deposited on a silicon wafer. The wafer surface is dipped in 0.8
wt. % agarose aqueous solution heated up to 80.degree. C. and is
then immediately placed in cool water to coat the surface with 10
micrometer (.mu.m) thick gel. The wafer is directly soaked in
copper electrolyte plating solution to grow a copper film with a
thickness of 50 nm or more, and then excessive agarose gel is
removed using water at a temperature of 80.degree. C. or more. A
cross-sectional sample of the film is produced through mechanical
polishing and ion milling and is observed by a transmission
electron microscope.
[0045] As application examples of the present invention, there are
considered, in addition to the semiconductor integrated circuit of
the specific example above, many applications such as a coating
film inside a mirror cylinder in which a lens as an optical part is
mounted, a surface layer of a gasket made of metal as an electric
tool, and a coating film of a blade of a razor as a mechanical
part.
[0046] Furthermore, for the obtained metallic material, part of the
three-dimensional mesh structure may be removed or denatured. For
example, in a case wherein the metallic material is employed as a
coating film of parts or the like in a high-vacuum apparatus, to
prevent the gel constituting the three-dimensional mesh structure
from contaminating the inside of the apparatus, it is possible to
remove or to regenerate the three-dimensional mesh structure
exposed to the surface of the compound metallic material. As a
method to remove part of the three-dimensional mesh structure,
there can be considered, for example, a method to remove a fixed
depth of the three-dimensional mesh structure from the surface of
the metallic material by an etching process, an oxygen plasma
process, or the like. Also, as a method to regenerate part of the
three-dimensional mesh structure, there can be considered, for
example, a method to cause, by heat treatment, reaction between the
three-dimensional mesh structure of the gel and the metal existing
in the vicinity of the surface of the metallic material. Even for
the metallic material in which the three-dimensional mesh structure
to be a core as above is lost, since the configuration of
dislocation is retained in the filled-in metal, the effects of the
mechanical strength, the durability against abrasion, the
resistivity against peel-off, and the like are kept unchanged.
[0047] The gel available in the embodiment includes gel of natural
material and gel of synthetic material as shown in Table 1; either
gel includes the three-dimensional mesh structure and is favorably
used as material including solvent in gaps.
TABLE-US-00001 TABLE 1 Primary category Secondary category Examples
of material Natural Polysaccharide Seaweed Galactoses (carageenan,
.beta.-D-galactose, Anhydro-.alpha.-D-galactose, material gel
polysaccharides agarose, etc.), Alginic
Anhydro-.alpha.-L-galactose, .beta.-D-mannuronic acid acid,
.alpha.-L-guluronic acid Plant Pectin, Konnyaku Protopectin, Pectic
acid, Pectinic acid polysaccharides mannan, Locust bean
(.alpha.-D-galacturonic acid), .beta.-D-glucose, gum, Cyamoposis
gum .beta.-D-mannose, .alpha.-D-galactose Microbe Gellan gum,
Xanthan Linear glucan, .beta.-D-glucose, .beta.-D-glucuronic
polysaccharides gum, Curdlan, Amino acid, .alpha.-L-rhamnose,
Mannose, acid gel Poly(.gamma.-glutamine), Poly(e-lysine) Protein
gel Protein in general (gelatin, white of boiled egg, tofu, etc.)
DNA gel DNA, RNA Synthetic Inorganic gel Oxides Silica gel, Alumina
gel, Titania gel material Salts of metal Nitrate Nanotubes Carbon
nanotube gel, Boron nitride nanotube gel Organic gel Salts of
organic Acetate, Salt of ethylhexanoic acid, Salt of neodecanoic
acid, Salt of acid octanoic acid Organic metals Alkoxide
(methoxide, ethoxide, butoxide, propoxide, isopropoxide,
methoxyethoxide, etc.), Acethylacetonate Crosslinked Polyvinyl
alcohol, poly acrylic acid, Acrylamide, Silicone, Polyurethane,
polymer Polyethylene oxide, Polyethylene glycol
[0048] As the gel of natural material, there can be considered gel
of polysaccharides, gel of protein, or DNA gel. Also, there may be
used gel including constituents extracted therefrom or the like.
The gels of polysaccharides include gel material such as seaweed
polysacharides, plant polysacharides, or microbe
polysaccharides.
[0049] As the gel materials of seaweed polysaccharides, there may
be considered galactoses (carageenan, agarose, etc.) or alginic
acid including, as a primary component, .beta.-D-galactose,
anhydro-.alpha.-D-galactose, anhydro-.alpha.-L-galactose,
.beta.-D-mannuronic acid, or .alpha.-L-guluronic acid.
[0050] As the gel materials of plant polysaccharides, there can be
considered pectin, Konnyaku mannan, locust bean gum, and cyamoposis
gum including, as a primary component, protopectin, pectic acid,
pectinic acid (.alpha.-D-galacturonic acid), .beta.-D-glucose,
.beta.-D-mannose or .alpha.-D-galactose.
[0051] As the gel materials of microbe polysaccharides, there can
be considered gellan gum, xanthan gum, curdlan, and amino acid gel
including, as a primary component, linear glucan,
.beta.-D-glucuronic acid, .alpha.-L-rhamnose, mannose,
poly(.gamma.-glutamine), or poly(.epsilon.-lysine).
[0052] As the gel materials to construct protein gels, there can be
considered polymer materials of protein in general such as gelatin,
the white of a boiled egg, or the like.
[0053] As gel materials to constitute DNA gel, DNA or RNA are
available.
[0054] As the gels of synthetic materials, there can be employed
inorganic gels produced using gel materials such as oxides, salts
of metal, or nanotubes or organic gels produced using gel materials
such as salts of organic acids, organic metals, or crosslinked
polymer.
[0055] As the gels produced using gel materials of oxides, there
can be considered silica gel, alumina gel, or titania gel. As
materials to produce silica gel, tetra methoxy silane is
available.
[0056] As the gel materials of metallic salts, nitrate is
available.
[0057] As the gel materials of nanotubes, carbon nanotube or boron
nitride tube is available.
[0058] As the gel materials of salts of organic acid, there can be
considered acetate, salt of ethylhexanoic acid, salt of neodecanoic
acid, or salt of octanoic acid.
[0059] As the gel materials of organic metals, there can be
considered alkoxide (methoxide, ethoxide, butoxide, propoxide,
isopropoxide, or methoxyethoxide) or acethylacetonate; for example,
copper methoxide and the like are available.
[0060] As the gel materials of crosslinked polymer, there can be
considered polyvinyl alcohol, poly(acrylic acid), acrylamide,
silicone, polyurethane, polyethylene oxide, or polyethylene
glycol.
[0061] The gel to be used as the three-dimensional mesh structure
may be gels other than gels exemplified above, and various gels are
available.
[0062] Furthermore, gel molecules as the gel materials may be
modified by atoms or molecules of an additive with the aim of
positively developing the effect of the additive.
[0063] The coating film of the metallic material of the embodiment
formed on the substrate is obtained by applying, on the substrate,
dispersing solution attained by dispersing gel material in
appropriate solvent, and then by filling metal therein using the
plating scheme.
[0064] Here, the solvent is required only to disperse the gel
material, and for example, organic solvent such as water or
methanol is available. Incidentally, "dispersion" here includes
both of mixing or dissolution.
[0065] Moreover, as the method of applying the dispersing solution,
there may be employed various applying methods such as a dip method
to dip the substrate in the dispersing solution, a spray method,
and a spin coating method. In this connection, the substrate (base
member) is a to-be-processed substrate (base member) on which the
metallic material is formed as a metallic film; for example, when
the metallic material is used as wiring, a semiconductor integrated
circuit substrate is the substrate here; when the metallic material
is used as various coating films, each of the electric tools or the
like to be coated with the film is the base member.
[0066] The production of gel on the substrate (base member) is
carried out using a method according to the kind of gel material
employed in which a crosslinking agent is added to the dispersing
solution or the dispersing solution applied onto the substrate
(base member) is cooled or heated to conduct gelatin
(crosslinking). For example, in a case wherein tetra methoxy silane
is adopted as the gel material, water is added thereto as an
additive for gelatin by hydrolysis reaction and polymerization
reaction; when polyvinyl alcohol is employed as the gel material,
aqueous solution of boric acid is added as a crosslinking agent to
conduct the gelatin. Moreover, when agarose is utilized, the
gelatin is performed by cooling the dispersion solution applied
onto the substrate (base member).
[0067] Metals which can be filled in using the plating scheme are,
for example, pure metals including Ag, Au, Cd, Co, Cr, Cu, Fe, Ni,
Pb, Pd, Pt, Rh, Ru, Si, Sn, or Zn; alloys including Ag--Cd, Ag--Co,
Ag--Cu, Ag--Sn, Ag--Zn, Al--Mn, Au--Cu, Au--Ni, Au--Pd, Au--Sn,
Cd--Sn, Cd--Zn, Co--Cu, Co--Fe, Co--Mo, Co--Ni, Co--Sn, Co--W,
Cr--H, Cu--Ni, Cu--Pb, Cu--Sb, Cu--Sn, Cu--Zn, Fe--Mo, Fe--Ni,
Fe--W, Fe--Zn, In--Sn, Ni--B, Ni--Mo, Ni--P, Ni--S, Ni--Sn, Ni--W,
Ni--Zn, or Sn--Zn; and compounds such as MgO or SnO2; the metal to
be filled in is selected from these metals and the like according
to various purposes of the use of metallic materials.
[0068] As the plating solution, there is employed aqueous solution
of sulfate, salt of sulfide, or pyrophosphate of the metal to be
filled in or solution of organic solvent including ethanol of salt
thereof, N-methylformamide, formamide, acetone, ethyl acetate,
benzene, dimethylsulfoxide, N-dimethylformamide, acetonitrile,
pyridine, tetrahydrofuran, or di-n-butyl ether.
[0069] As the plating solution, there can be specifically employed
those shown in Table 2. That is, as the Ag plating solution, a
silber iodide bath: AgI (0.05 mol/L)+KI (2 mol/L) is available; as
the Au plating solution, there can be used a cyanogen bath:
KAu(CN).sub.2 (0.05 mol/L), a sulfurous acid bath:
Na.sub.3Au(SO.sub.3).sub.2 (0.05 mol/L), or a chloroaurate bath:
HAuCl.sub.4 (0.02 mol/L) is available. Furthermore, as the Cr
plating solution, a Sargent bath: CrO3 (2.5 mol/L)+H.sub.2SO.sub.4
(0.025 mol/L) is available; as the Cu plating solution, a Cu
sulfate bath: CuSO.sub.4.H.sub.2O (1.0 mol/L) or a pyrophosphoric
acid bath: CuP.sub.2O.sub.7.3H.sub.2O (0.2
mol/L)+KP.sub.2O.sub.7.3H.sub.2O (0.7 mol/L) is available.
Additionally, as the Fe plating solution, a sulfuric acid bath:
FeSO.sub.4 (1.0 mol/L)+H.sub.3BO.sub.3 (0.5 mol/L), a chloride
bath: FeCl.sub.2 (1.0 mol/L)+H.sub.3BO.sub.3 (0.5 mol/L), or a
sulfaminic acid bath: Fe(S.sub.2NH.sub.2).sub.2 (1.0
mol/L)+HFNH.sub.4 (0.1 mol/L) is available. Moreover, as the Ni
plating solution, a sulfrate bath: NiSO.sub.4 (1.0
mol/L)+H.sub.3BO.sub.3 (0.5 mol/L), a chloride bath: NiCl.sub.2
(1.0 mol/L)+H.sub.3BO.sub.3 (0.5 mol/L), a Watt bath: NiSO.sub.4
(0.9 mol/L)+NiCl.sub.2 (0.09 mol/L)+H.sub.3BO.sub.3 (0.5 mol/L), or
a sulfamine acid bath: Ni(S.sub.2NH.sub.2).sub.2 (1.0
mol/L)+H.sub.3BO.sub.3 (0.5 mol/L) is available. As specific
examples of alloy plating solution, there can be employed, as the
Ag--Sn alloy plating solution, AgI (0.02
mol/L)+SnCl.sub.2.2H.sub.2O (0.18 mol/L)+KI (2
mol/L)+K.sub.4P.sub.2O.sub.7 (0.54 mol/L) is available; as the
Cu--Sn alloy, there can be used SnSo.sub.4 (X mol/L)+CuSO.sub.4
(0.5 mol/L)+cresolsulfonic acid (0.25 mol/L).
TABLE-US-00002 TABLE 2 Metal Plating solution example Ag Silber
iodide bath: AgI (0.05 mol/L) + KI (2 mol/L) Au Cyanogen bath:
KAu(CN).sub.2 (0.05 mol/L) Sulfurous acid bath:
Na.sub.3Au(SO.sub.3).sub.2 (0.05 mol/L) Chloroaurate bath:
HAuCL.sub.4 (0.02 mol/L) Cr Sargent bath: CrO.sub.3 (2.5 mol/L) +
H.sub.2SO.sub.4 (0.025 mol/L) Cu Sulfuric acid bath:
CuSO.sub.4.cndot.H.sub.2O (1.0 mol/L) Pyrophosphoric acid bath:
CuP.sub.2O.sub.7.cndot.3H.sub.2O (0.2 mol/L) +
KP.sub.2O.sub.7.cndot.3H.sub.2O (0.7 mol/L) Fe Sulfuric acid bath:
FeSO.sub.4 (1.0 mol/L) + H.sub.3BO.sub.3 (0.5 mol/L) Chloride bath:
FeCl.sub.2 (1.0 mol/L) + H.sub.3BO.sub.3 (0.5 mol/L) Sulfamic acid
bath: Fe(S.sub.2NH.sub.2).sub.2 (1.0 mol/L) + HFNH.sub.4 (0.1
mol/L) Ni Sulfuric acid bath: NiSO.sub.4 (1.0 mol/L) +
H.sub.3BO.sub.3 (0.5 mol/L) Chloride bath: NiCl.sub.2 (1.0 mol/L) +
H.sub.3BO.sub.3 (0.5 mol/L) Watt bath: NiSO.sub.4 (0.9 mol/L) +
NiCl.sub.2 (0.09 mol/L) + H.sub.3BO.sub.3 (0.5 mol/L) Sulfamic acid
bath: Ni(S.sub.2NH.sub.2).sub.2 (1.0 mol/L) + H.sub.3BO.sub.3 (0.5
mol/L) Ag--Sn AgI (0.02 mol/L) + SnCl.sub.2.cndot.2H.sub.2O (0.18
mol/L) + KI (2 mol/L) + K.sub.4P.sub.2O.sub.7 (0.54 mol/L) Cu--Sn
SnSO.sub.4 (X mol/L) + CuSO.sub.4 (0.5-X mol/L) + H.sub.2SO.sub.4
(1 mol/L) + Cresolsulfonic acid (0.25 mol/L)
BRIEF DESCRIPTION OF DRAWINGS
[0070] FIG. 1 is a schematic cross-sectional view for explaining
action of metallic material of the embodiment.
[0071] FIG. 2 is a schematic cross-sectional view for explaining a
constitution of metallic material of the embodiment.
[0072] FIG. 3 is a schematic diagram showing an example of metallic
material of the embodiment.
[0073] FIG. 4 is a transmission electron microscope image showing a
specific example of metallic material of the embodiment. FIG. 4(a)
shows a transmission electron microscope image of a crystal grain
in a film in which agarose gel is filled in copper with electron
beam incidence orientation <211> and FIG. 4(b) shows a
transmission electron microscope image of a crystal grain in a film
in which agarose gel is filled in copper with electron beam
incidence orientation <011>.
BRIEF DESCRIPTION OF REFERENCE NUMERALS
[0074] 101 Substrate [0075] 102 Gel (three-dimensional) mesh
structure [0076] 103 Metal [0077] 201 Gel network (observation is
difficult) [0078] 202 Subdivided moire patterns [0079] 203 Size of
subdivided areas of moire patterns [0080] 301 Dislocation contrast
[0081] 302 Dislocation contrast [0082] 303 Dislocation contrast
[0083] 401 Metal [0084] 402 Grain interface [0085] 403 Tensile
stress [0086] 404 Void [0087] 405 Dislocation [0088] 406 Gel mesh
structure (solid line) [0089] 407 Gel mesh structure (broken
line)
* * * * *